<?php
var_dump((0.1+0.7)*10, floor((0.1+0.7)*10));

//精确度测试
$a = 1.99;
$b = 2.99;
echo $a+$b;

var_dump(+0,-0,(string)+0);

var_dump(min(100, "0.50", ''));

var_dump(round(0.5004,2),sprintf("%.2f", 0.5004), sprintf("%+.2f", 0.5004), sprintf("%-8.2f", 0.5004));